Method of producing charts for testing color vision



Feb. 7, 1928.

E. SCHAAFF METHOD OF PRODUCING CHARTS FOR TESTING COLOR VISION FiledApril 20. 1926 "llllllllllllw INVENTOR.

XTTORNEY.

Patented Feb. 7, 1928. V f 7 1,658,356

UNITED STATES PATENT OFFICE.

ERNEST SCI-IAAFF, on STRASBOURG; FRANCE, METHOD on PRODUCING CHARTS FORTES ING COLOR VISION. Application filed April 20, 1926', Serial No.103,372, and in France May 28, 1925.

For testing color vision printed charts tone obtained by very finelines, which may are usually employed each of which combe replaced bydots, and a deep or saturated 45, prises two or more confusing colors.It is tone constituted by an uninterrupted patch, well known that inorder to produce the tie and passing through an almost unlimited siredeil-ect such colors must have equal ingamut of intermediate tonesobtained by tensities, which in practice if not impossible, the crossingor superposition of difi'erent is at least-very diflicult to obtain bymeans figures, or by the use of lines progressively of the usuallithographic methods." In order thicker and disposed more closelytogether, to remedy this defect it has been proposed if desired inchequers ofvarious conforma- 1" to employ charts comprising confusingcol' tions;

ors oi difierent shades. 7 It, is obvious that the carrying out of theBy the present invention, I propose to sim above described process mustbe adapted to plify the manufacture of such charts and the nature of thecharts to be produced, and to render them more practical and more thesurfaces of colors are subject to the economical, and this I accomplishby groupmost diverse variations in shape, size and ing on a single charta plurality oi preferdistribution. Thus they may be presented ablypolygonal surfaces of two. different in the shape of squares, or anyother geo- 6 colors of various shadesor intensities. Thus, metricalort'ancy figures so as to form the by using a cross-hatcliing consistingof finev most varied designs.

0 lines of the particular color and intersecting Specimens have beenfiled to illustrate this one or more times, or by employing dots, ordescription.

any other method of graphic representation, The single figure of theaccompanying I can produce a surface having a veryclear drawing shows,by way of example, a poror light tone, whilst by thicker and more tionofa chart produced in accordance with closely arranged lines or dots,the impression applicants invention. 7 This portion contains of a darkeror more saturated shade is impolygonal figures 4, a a a a tinted,'torparted to the observer. 7 instance, red, and polygonal figures b, I),72?, By a iudicious choice -of lines full dotted, Z1, 6 "tinted, forinstance, green. These mixed, etc.,and their disposition, thicknesspolygonal figures are obtained by more or Q and direction, an entiregamut of sensations less closecross-hatching in such a way that ofshades can be obtained with a single base various shades of red, e. g.four,and various color, and themultiple color impression is shades ofgreen, e. g. four, result, va-i'yii1g75.

transformed in this manner as regards each from deep red or deep greento very light color into an impression of a singlecolor red and verylight green respectively.

5 of different values giving the sensation of I claim:

several shades and masking in consequence A chart for testing the colorsense of the the lithographic defects, unsuitable for human eyecomprising a single surface, such juxtaposing two confusing colorswhich, in as a sheet of paper, provided with a pluorder to be able to beconfounded bythe i'ality ot isolated patches in two'colors oi colorblind must be oi? precisely equal values. varying shades produced bylines or dots ar- By proceeding in the above manner, with a ranged moreor less closely together. single base color, one can obtain colorpatches In testimony whereof I affix my signature.

varying between a scarcely perceptible pale ERNEST SCTHAAFF.

